1. Technical Field
The present invention relates to a manufacturing method of a semiconductor device for forming a film such as silicon or silicon germanium on a silicon substrate.
2. Background Art
Generally, a silicon substrate is used as a semiconductor substrate, and on a silicon surface and on a substrate having an insulating film such as a silicon nitride film, a technique of allowing an epitaxial film to selectively grow only on the silicon surface is studied. Note that a selective growth refers to the technique of allowing a film to selectively grow only on the surface of silicon.
For example, although further micronization and high performance of MOSFET (Metal-Oxide-Semiconductor-Field-Effect-Transistor) is progressed, low resistance tendency of a contact resistance is given as a problem for forming a source/drain of the MOSFET, and as one of the methods for solving such a problem, an attempt to allow a silicon epitaxial film to grow on the source/drain.
Also, in recent years, the following technique has been focused. Namely, the source/drain is etched in a recess state, and a scraped source/drain part is doped with C (carbon), etc, having a different lattice constant to allow the silicon epitaxial film to selectively grow thereon, thus giving a strain to a channel, so that a high performance of a transistor is realized.
Incidentally, in case of the selective growth of silicon or silicon germanium, etc, a natural oxide film or impurities on the substrate must be removed. As such a processing method, a hydrogen reduction method is used, wherein H2 gas is used as a reductive gas.
However, in order to obtain a sufficient effect by the hydrogen reduction method, reduction processing needs to be performed at a high temperature of 800° C. or more, thus making a problem more serious, such as a thermal damage of a substrate element and increase of a thermal budget. Also, in a conventional method, there is a problem that pre-cleaning process by dilute hydrofluoric acid, etc, is required before reduction processing, thus taking a lot of trouble over such a pre-cleaning.
Therefore, an object of the present invention is to provide a manufacturing method of a semiconductor device capable of realizing the selective growth at a low temperature.